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Updated: Jun 22, 2026
Inhibition of Aspergillus flavus Growth and Aflatoxin Production in Transgenic Maize Expressing the α-amylase Inhibitor from Lablab purpureus L.
Published on: February 15, 2019
Aflatoxin and ochratoxin production by Aspergillus species under ex vivo conditions
Maren A Klich1, Sean Tang, David W Denning
1USDA, ARS, Southern Regional Research Center, New Orleans, LA 70124, USA. maren.klich@ars.usda.gov
Abstract:
Aspergillus species are increasingly important human pathogens. It is not known whether toxic metabolites of many of these pathogenic species can act as virulence factors in aspergillosis. We examined isolates of aflatoxin and ochratoxin-producing species for toxin production in ex vivo conditions. Seven of the 21 aflatoxin-producing isolates screened produced aflatoxin at 35 and 37 degrees C on the general medium yeast extract sucrose agar (YES). However, none of them produced toxin at these temperatures on brain heart infusion agar (BHA), a medium that mimics human tissue, or on BHA with modified pH or sugar levels. Six of the 12 ochratoxin-producing isolates examined produced toxin at 35 degrees C on YES. All three isolates of A. alliaceus produced ochratoxin on BHA or modified BHA at 37 degrees C. One strain of A. pseudoelegans produced a minute amount of ochratoxin on modified BHA at 37 degrees C. These data indicate that aflatoxin is an unlikely virulence, factor but that ochratoxin may be a potential virulence factor in aspergillosis.
Insights
Aflatoxin is unlikely to be a virulence factor in aspergillosis, as it was not produced on human tissue-mimicking media. Ochratoxin, however, may be a potential virulence factor in aspergillosis.
Area of Science:
- Medical Mycology
- Pathogen Toxinology
Background:
- Aspergillus species are emerging as significant human pathogens.
- The role of toxic metabolites as virulence factors in aspergillosis remains largely uncharacterized.
Purpose of the Study:
- To investigate the potential of aflatoxin and ochratoxin as virulence factors in aspergillosis.
- To assess toxin production by Aspergillus species under ex vivo conditions.
Main Methods:
- Screening of aflatoxin and ochratoxin-producing Aspergillus isolates.
- Toxin production assays were performed on yeast extract sucrose agar (YES) and brain heart infusion agar (BHA) at physiological temperatures (35°C and 37°C).
- BHA was modified with altered pH and sugar levels to simulate human tissue conditions.
Main Results:
- Aflatoxin production was detected in 7/21 isolates on YES at 35°C and 37°C, but not on BHA or modified BHA.
- Ochratoxin was produced by 6/12 isolates on YES at 35°C.
- Significant ochratoxin production was observed from Aspergillus alliaceus on BHA and modified BHA at 37°C, with one Aspergillus pseudoelegans strain producing a minor amount.
Conclusions:
- Aflatoxin is unlikely to function as a virulence factor in aspergillosis due to its inability to be produced on human tissue-mimicking media.
- Ochratoxin demonstrates potential as a virulence factor in aspergillosis, given its production under simulated physiological conditions.
